1. Technical Field
The present invention relates to an embedded printed circuit board (PCB) in which an electronic component is embedded and, more particularly, to an embedded printed circuit board in which surfaces of electronic components embedded therein are used as a wiring space to thus simplify a layer configuration and optimize wiring on a substrate, and a manufacturing method thereof.
2. Description of the Related Art
A printed circuit board (PCB), formed by printing line patterns with a conductive material such as copper on an electrically insulating substrate, refers to a substrate immediately before electronic components are mounted thereon. Namely, in order to closely mount a large number of various types of electronic components on a flat plate, mounting positions of the respective components are determined and circuit patterns connecting the components are fixedly printed on the surface of the flat plate.
Among methods for mounting components on the line pattern PCB, a surface mount technique (SMT) has normally been used. The SMT is a method for attaching surface mounted components (SMCs), which can be directly mounted on the surface of the PCB, to electronic circuits. The electronic devices manufactured thusly are called surface-mounted devices (SMDs).
In an electronic industry, the SMT is replacing a through hole technology attachment scheme using a component for inserting an element pin into a hole of a PCB. In general, SMCs are smaller than the same through hole components. The reason is because pins of the SMCs may be shorter or may be omitted. SMCs have shorter pins, and there are various types of packages such as a surface contact type package, a ball grid array (BGA) type package, a package including pins protruded from components thereof, and the like.
In comparison to the old through hole technology, the SMT has the following advantages. Namely, the components are smaller and more lightweight, a board can be processed with a smaller hole, components can be simply and automatically assembled, and components are automatically disposed precisely with a small amount of error (surface tension of melted solder pulls component pins to a solder pad to arrange it at an accurate position).
Also, components can be attached to both sides of the PCB, and resistance and impedance of the component pins are reduced (performance and operating frequency of the components are increased). Also, the components have excellent mechanical performance in a wobbling or vibration state, and in general, the SMCs are cheaper than through hole components, the SMT causes less unnecessary RF signal effect than that of the through hole technology, and flexibility of component characteristics is considerably enhanced.
In line with the development of the electronics industry, electronic components are increasingly required to be multifunctional and have a smaller size, and in particular, a trend in the market based on lighter, thinner, shorter, and smaller personal mobile terminals leads to a reduction in thickness of PCBs. Accordingly, a device mounting scheme, which is different from the existing device mounting scheme, has emerged. That is, an embedded PCB in which active components such as an IC or the like, or passive components such as a capacitor, for example, a multilayered ceramic component (MLCC), or the like, are mounted to enhance high density and reliability or organically coupled to pursue enhancement of a package itself.
Unlike the related art PCB in which passive elements and active elements share the surface of the PCB, the embedded PCB is configured such that passive elements such as a resistor, a capacitor, or the like, or active elements such as an IC, or the like, are embedded in the substrate, securing an extra space on the surface of the PCB, and in comparison to the related art PCB, wiring density can be enhanced to develop a more compact electronic device.
Also, since the elements are connected in a vertical direction, a wiring length is drastically reduced, which leads to a reduction in generation of impedance due to a parasitic effect and a problem such as signal delay, or the like, in an electronic device. For these reasons, an embedded active/passive device (EPAD) technology has come to prominence in order to enhance integration.
However, the embedded PCB requires a space to be secured for connecting electrodes of the electronic component embedded therein, and a portion where the component is embedded is not available for via processing, or the like. Thus, in case in which a different component is mounted on the surface of the substrate or the surface wiring is complicated, a layer must be added.